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PubMed1988

Physiological effects of portal ligation on the longitudinal and circular muscles of the dog portal tree.

We studied physiological effects of portal vein ligation on the longitudinal and circular muscles of the dog portal tree. Portal venous blood pressure after portal ligation was higher in dogs that died than in those that survived. The portal veins isolated from dogs that died after portal ligation exhibited both lower rate of onset and decreased intensity of spontaneous activity, compared with those from dogs that survived. Responsiveness of longitudinal muscles of each of the four portal segments to noradrenaline, acetylcholine, histamine and KCl was markedly reduced in dogs that died, compared with those that survived, although the responsiveness of circular muscle was nearly equal in both groups of dogs. The longitudinal muscle of the truncal portal vein from dogs that died responded less strongly to electrical transmural stimulation than that from surviving dogs. The nonadrenergic, noncholinergic response was almost abolished in dogs that died rapidly. The degree of spontaneous activity or responsiveness to various stimulations in smooth muscles of the portal tree is considered to reflect muscular development. The degree of development of the longitudinal muscle of the portal tree may determine the survival of dogs after portal ligation.

Acetylcholine↗
PubMed1990

Rat intestinal iron transfer capacity and the longitudinal distribution of its adaptation to iron deficiency.

The longitudinal gradient of intestinal iron transfer was investigated in normal and iron-deficient male Sprague-Dawley rats in vitro and in vivo. In normal rats in vitro iron transfer in the duodenum was approximately 3 times higher than in the jejunum and decreased in the ileum to approximately half the jejunal values. Compared to the controls in vitro iron transfer was increased 3-4 times in the duodenum and in the first jejunal segment and 2-3 times in the second jejunal segment. No significant adaptation to iron deficiency was found in the rest of the small intestine. Iron transfer rates showed the same longitudinal pattern when iron was chelated with nitrilotriacetic acid (NTA) or with ascorbate. The absorbed iron quantities, however, were approximately 5 times lower when Fe-ascorbate was used, which might be due to differences in bioavailability. Omission of Fe-NTA and Fe-ascorbate had no impact on the vitality of the segments. Glucose transfer was used as vitality criterion. It was not significantly different between corresponding iron-deficient and control segments. To control these results in vivo mesenteric blood was collected from duodenal and jejunal segments in situ. Corresponding to in vitro findings iron transfer was close to linear over the experimental period. In iron deficient duodenal segments iron transfer increased approximately 3 times as compared to controls while no adaptational changes were found in the distal jejunum. No significant longitudinal gradient was found in the mucosal content of ferritin and nonheme iron. Both parameters were decreased in iron deficiency by about half. The mucosal transferrin content showed no longitudinal gradient in control animals. In iron deficiency transferrin was significantly increased in the duodenum and in the three most proximal jejunal segments. The results indicate that in rats adaptation of iron absorption to the demand can only be expected in the duodenum and in the proximal 20 cm of the jejunum. Because this process shows a steep gradient in the proximal small intestine, studies on the adaptation of intestinal iron transfer to the demand should use short and well-defined segments in order to provide reproducible results.

Adaptation, Physiological↗
PubMed2002

Anisotropic conduction properties in canine atria analyzed by high-resolution optical mapping: preferential direction of conduction block changes from longitudinal to transverse with increasing age.

BACKGROUND: Anisotropic conduction properties may provide a substrate for reentrant arrhythmias. We investigated the age-dependent changes of structural and functional anisotropy in isolated right atria from infant (1 to 2 months), young (6 to 12 months), and old (6 to 10 years) dogs. METHODS AND RESULTS: The histology of the mapped atrial tissues (a small subepicardial area, 2.8x4.2 mm) was characterized by an age-dependent increase of myofiber width and fat cell infiltration between myofibers. Cx43 was distributed homogeneously over the entire cell surface in infant dogs, whereas it progressively polarized to the cell termini with increasing age. The activation sequences were analyzed by high-resolution optical mapping using a voltage-sensitive dye. Activation fronts from the pacing site proceeded more rapidly along fiber orientation (longitudinal) than across it (transverse). Infant dogs showed "elliptical" isochrones with a smooth transition between longitudinal and transverse propagation, whereas old dogs had a "square" pattern with a sharp transition. Conduction block occurred predominantly during longitudinal propagation in infant dogs but during transverse propagation in old dogs. The shape of the wave front and the degree of lateral uncoupling seemed to decide the preferential direction of block. A zigzag activation causing an extremely slow transverse conduction was observed only in old dogs. CONCLUSIONS: Along with the age-dependent structural anisotropy, the preferential direction of block changed from longitudinal to transverse in association with a change in the wave front configuration. A zigzag propagation based on lateral uncoupling would predispose the elderly to multiple reentry and a higher incidence of atrial fibrillation.

Action Potentials↗
PubMed2000

The MR imaging appearance of longitudinal split tears of the peroneus brevis tendon.

PURPOSE: Longitudinal split tears of the peroneus brevis tendon have been increasingly reported as a source of lateral ankle pain and disability. MR imaging is useful in identifying the appearance of longitudinal split tears of the peroneus brevis tendon to differentiate this entity from other causes of chronic lateral ankle pain. We observed variations in anatomy associated with these tears. MATERIALS AND METHODS: Twenty-two patients (eleven males, eleven females) were identified as having longitudinal split tears of the peroneus brevis tendon. These cases were reviewed retrospectively to evaluate for the following: shape of the peroneus brevis tendon, high signal in the peroneus brevis tendon, tendon subluxation, appearance of the superior peroneal retinaculum, presence of osseous changes in the ankle, lateral ankle ligaments, presence of a bony fibular spur, flattening of the peroneal groove of the fibula and presence of a peroneus quartus. A control group consisted of twenty ankles imaged for reasons other than lateral ankle pain. The same structures were assessed in this group. A Fisher's exact P-value was used to determine the significance of each finding in the two groups. RESULTS: Statistically significant associated findings were chevron shaped tendon (p = .0001), high signal in the peroneus brevis (p = .0017), bony changes (p = .0001), flat peroneal groove (p = .0001), abnormal lateral ligaments (p = .0004), and lateral fibular spur (p = .0006). CONCLUSIONS: MR imaging is useful in differentiating longitudinal split tears of the peroneus brevis tendon from other lateral ankle disorders. It can show the extent of the abnormality in the tendon and the associated findings of soft tissue and/or bone variations which must be addressed at the time of surgery.

Adolescent↗
PubMed1998

Effects of fibroblast growth factor-2 on longitudinal bone growth.

In vivo, fibroblast growth factor-2 (FGF-2) inhibits longitudinal bone growth. Similarly, activating FGF receptor 3 mutations impair growth in achondroplasia and thanatophoric dysplasia. To investigate the underlying mechanisms, we chose a fetal rat metatarsal organ culture system that would maintain growth plate histological architecture. Addition of FGF-2 to the serum-free medium inhibited longitudinal growth. We next assessed each major component of longitudinal growth: proliferation, cellular hypertrophy, and cartilage matrix synthesis. Surprisingly, FGF-2 stimulated proliferation, as assessed by [3H]thymidine incorporation. However, autoradiographic studies demonstrated that this increased proliferation occurred only in the perichondrium, whereas decreased labeling was seen in the proliferative and epiphyseal chondrocytes. FGF-2 also caused a marked decrease in the number of hypertrophic chondrocytes. To assess cartilage matrix synthesis, we measured 35SO4 incorporation into newly synthesized glycosaminoglycans. Low concentrations (10 ng/ml) of FGF-2 stimulated cartilage matrix production, but high concentrations (1000 ng/ml) inhibited matrix production. We conclude that FGF-2 inhibits longitudinal bone growth by three mechanisms: decreased growth plate chondrocyte proliferation, decreased cellular hypertrophy, and, at high concentrations, decreased cartilage matrix production. These effects may explain the impaired growth seen in patients with achondroplasia and related skeletal dysplasias.

Animals↗
PubMed2003

The dead ringer/retained transcriptional regulatory gene is required for positioning of the longitudinal glia in the Drosophila embryonic CNS.

The Drosophila dead ringer (dri, also known as retained, retn) gene encodes a nuclear protein with a conserved DNA-binding domain termed the ARID (AT-rich interaction domain). We show here that dri is expressed in a subset of longitudinal glia in the Drosophila embryonic central nervous system and that dri forms part of the transcriptional regulatory cascade required for normal development of these cells. Analysis of mutant embryos revealed a role for dri in formation of the normal embryonic CNS. Longitudinal glia arise normally in dri mutant embryos, but they fail to migrate to their final destinations. Disruption of the spatial organization of the dri-expressing longitudinal glia accounts for the mild defects in axon fasciculation observed in the mutant embryos. Consistent with the late phenotypes observed, expression of the glial cells missing (gcm) and reversed polarity (repo) genes was found to be normal in dri mutant embryos. However, from stage 15 of embryogenesis, expression of locomotion defects (loco) and prospero (pros) was found to be missing in a subset of LG. This suggests that loco and pros are targets of DRI transcriptional activation in some LG. We conclude that dri is an important regulator of the late development of longitudinal glia.

Animals↗
PubMed1982

Fine structure of the longitudinal flagellum in Ceratium tripos, a marine dinoflagellate.

The fine structure of the longitudinal flagellum in Ceratium tripos, which performs not only undulations but also retractions, has been examined in both the retracted and relaxed states. Although conventional fixation always triggered retraction, the flagellum was found to remain relaxed when it was washed briefly with Ca2+-free medium prior to fixation. Previous light-microscopic investigation showed that it contained two fibres, the axoneme and the R-fibre. The present study by transmission electron microscopy has revealed that the axoneme that appeared to be a single fibre under the light microscope is a bundle of four fibres; the 9 + 2 microtubular axoneme, the packing material, the striated fibre, and the paraxial fibre. The first two are common in the longitudinal flagella of dinoflagellates, and the axoneme presumably generates the undulation. The last two are new and unique to the longitudinal flagellum of Ceratium. The R-fibre, which probably contracts to fold the flagellum during retraction, consists of fine filaments, which pursue a loosely spiral course in the contracted state, but align longitudinally in the relaxed state. Periodic striations appear only on the extended R-fibre. The R-fibre shortens to approximately one third of its extended length and pursues a left-handed helix. The packing material, which sticks to the microtubular axoneme on one side, is connected with the R-fibre on the other side at intervals of approximately 5.8 micrograms. The retraction seems to be regulated by the Ca2+ concentration in the flagellum.

Animals↗
PubMed2004

Functional roles of the transverse and longitudinal flagella in the swimming motility of Prorocentrum minimum (Dinophyceae).

Equations describing the motion of the dinoflagellate Prorocentrum minimum, which has both a longitudinal and a transverse flagellum, were formulated and examined using numerical calculations based on hydrodynamic resistive force theory. The calculations revealed that each flagellum has its own function in cell locomotion. The transverse flagellum works as a propelling device that provides the main driving force or thrust to move the cell along the longitudinal axis of its helical swimming path. The longitudinal flagellum works as a rudder, giving a lateral force to the cell in a direction perpendicular to the longitudinal axis of the helix. Combining these functions results a helical swimming motion similar to the observed motion. Flagellar hairs present on the transverse flagellum are necessary to make the calculated cell motion agree with the observed cell motion.

Animals↗
PubMed1977

Oscillating contractions in protoplasmic strands of Physarum: simultaneous tensiometry of longitudinal and radial rhythms, periodicity analysis and temperature dependence.

1. The construction of a 'twin-tension transducer' allows the simultaneous measurement of the same or different contraction rhythms at any selected sites of living plasmodia of Physarum polycephalum. This method has been used to analyse the relation of longitudinal and radial contraction activity within migrating plasmodia and plasmodial veins, under isometric as well as under isotonic conditions of measurement. 2. A periodicity analysis of the oscillating contraction rhythms revealed average period values for the longitudinal contraction cycle of 2-1 min and for the radial contraction cycle of 1-3 min at a temperature of 22 degrees C. 3. The periods of longitudinal contraction depend on the environment of the strands. The mean value under submerged conditions was 2-9 min. 4. The temperature dependences for both longitudinal and radial contraction cycles were determined to provide reliable values for the normal reaction range of the contractile system (cytoplasmic actomyosin). The values for radial contraction activity are 2-0 min at 16 degrees C, 1-5 min at 20 degrees C, and 1-2 min at 24 degrees C. The range between 16 degrees and 24 degrees C can be regarded as physiological. 5. The possibility is discussed that only one 'genuine' contraction frequency of cytoplasmic actomyosin exists in Physarum.

Cytoplasm↗
PubMed2006

Shoe midsole longitudinal bending stiffness and running economy, joint energy, and EMG.

PURPOSE: It has been shown that mechanical energy is dissipated at the metatarsophalangeal (MTP) joint during running and jumping. Furthermore, increasing the longitudinal bending stiffness of the midsole significantly reduced the energy dissipated at the MTP joint and increased jump performance. It was hypothesized that increasing midsole longitudinal bending stiffness would also lead to improvements in running economy. This study investigated the influence of midsole longitudinal bending stiffness on running economy (performance variable) and evaluated the local effects on joint energetics and muscular activity. METHODS: Carbon fiber plates were inserted into running shoe midsoles and running economy, joint energy, and electromyographic (EMG) data were collected on 13 subjects. RESULTS: Approximately a 1% metabolic energy savings was observed when subjects ran in a stiff midsole relative to the control midsole. Subjects with a greater body mass had a greater decrease in oxygen consumption rates in the stiff midsole relative to the control midsole condition. The stiffer midsoles showed no significant differences in energy absorption at the MTP joint compared with the control shoe. Finally, no significant changes were observed in muscular activation. CONCLUSION: Increasing midsole longitudinal bending stiffness led to improvements in running economy, yet the underlying mechanisms that can be attributed to this improvement are still not fully understood.

Adult↗
PubMed1977

[Contractile responses of the guinea pig ileal longitudinal muscle to antispasmodics (author's transl)].

Papaverine, benactyzine and Aspaminol were found to induce strong contractions of guinea pig ileal longitudinal muscle in a medium containing 3.2 mM of Ca2+. The contractile actions of papaverine, benactyzine and Aspaminol were potentiated with increase in Ca2+. The contractile actions of papaverine, benactyzine and action of papaverine was completely blocked by Mn2+, which by itself caused a contraction of the longitudinal muscle. The maximal contraction by papaverine was obtained at the concentration of more than 10(-5) M, WHILE BOTH BENACTYZINE AND Aspaminol induced the maximal contractions at the concentration of 3 X 10(-4) M. During and after the contraction by papaverine, contractile responses to benactyzine and Aspaminol were not observed. Changes in the intracellular level of cyclic GMP after exposure of the longitudinal muscle to papaverine, benactyzine or Aspaminol did not occur. These results suggest that papaverine, benactyzine Aspaminol may induce contractions of the ileal longitudinal muscle through a similar mechanism of action. A likely assumption is that these drugs move intracellular bound Ca2+ to the contractile protein of the muscle.

Acetylcholine↗
PubMed1995

Spontaneous tone in different types of longitudinal muscle preparations of guinea pig ileum.

Spontaneous tone of longitudinal muscle in guinea pig ileum was investigated in three types of preparations, intact segment preparation, segment preparation deprived of the mucosal layer and longitudinal strip preparation. Tone was defined as the sustained contraction that was lost by 10(-7) M atropine in the isotonically recorded manner. The magnitudes of tone were constant for at least 3 hr in the two types of segment preparations. Contractions in response to 10(-6) M acetylcholine, which were induced 9 times with an interval of 20 min between each induction, were almost identical throughout the period. In the longitudinal strip preparation, on the other hand, the tone gradually decayed and was eventually lost, while the amplitudes of acetylcholine-induced contractions were reciprocally increased. The tone in the intact segment preparation was reduced to 19% of the control by tetrodotoxin (3 x 10(-7) M), to 51% by indomethacin (3 x 10(-6) M) and to 26% by N6-cyclopentyladenosine (10(-7) M), but was not affected by AA-861 (3 x 10(-6) M) or CP-96,345 (3 x 10(-7) M). In the three types of preparations, the dose-response curves for acetylcholine were alike with similar EC50s. These results suggest that the tone of longitudinal muscle was mainly induced due to neural activity in the myenteric plexus of guinea pig ileum and that sensitivity to acetylcholine was not affected by the neural activity.

Acetylcholine↗
PubMed2005

Slit-roundabout signaling neutralizes netrin-Frazzled-mediated attractant cue to specify the lateral positioning of longitudinal axon pathways.

An extending axon growth cone is subjected to attractant and repellent cues. It is not clear how these growth cones discriminate the two opposing forces and select their projection paths. Here, we report that in the Drosophila nerve cord the growth cones of longitudinal tracts are subjected to attraction by the Netrin-Frazzled pathway. However, the midline Slit neutralizes this pathway in a Robo-dependent manner and prevents Netrin-Frazzled-mediated attraction of longitudinal tracts. Our results suggest that the loss of a neutralizing effect on the Netrin-mediated attraction is responsible for the longitudinal tracts entering the midline in slit mutants as opposed to a loss of repulsion as is currently believed. This effect is not via a direct inhibition of Frazzled by Robo; instead, it is at a level downstream of Frazzled. Thus, the growth cones of longitudinal tracts subjected to two opposing forces are able to block one with the other and specify their correct lateral positioning along the midline.

Animals↗
PubMed1994

Contractile responses of longitudinal muscle strip to 5-HT and influences of divalent cations in the guinea-pig isolated colon.

The contractile effects of 5-hydroxytryptamine (5-HT) and influences of several kinds of divalent cations were investigated on longitudinal muscle strips of the guinea-pig isolated distal colon. 5-HT (10 nM-10 microM) produced phasic contractions which were partially inhibited by atropine (1 microM) and markedly inhibited by tetrodotoxin (1 microM), indicating that 5-HT acts mainly on the myenteric plexus and releases transmitters to cause contraction of the longitudinal muscle. The contractile response to 5-HT (3 microM) was almost completely inhibited by spantide (10 microM), a substance P antagonist, in the presence of atropine (1 microM), while spantide alone did not block 5-HT-induced contraction. Of several divalent cations including Cd2+, Co2+, Mg2+, Mn2+, Ni2+, Sr2+ and Zn2+, Cd2+ ions (10 mu-100 microM), which block L- and N-type Ca2+ channels, were most effective inhibitor of the 5-HT-induced contractions. While Sr2+ and Co2+ at a concentration of 100 microM did not have a significant effect. The order effectiveness of inhibition was Cd2+ >> Mn2+ > Mg2+ = Ni2+ = Zn2+. Bay K 8644 (1 microM), a L-type Ca2+ channel activator, did not influence the contractile response of the longitudinal muscle strip to 5-HT (3 microM). The present results suggest that 5-HT may mainly act on N-type Ca2+ channels in the myenteric neurones and cause the release of at least acetylcholine and substance P to induce contractions of the longitudinal muscle in the guinea-pig distal colon.

Acetylcholine↗
PubMed1994

Oblique smooth muscle bundles between the circular and longitudinal muscle layers in the canine proximal colon.

The region between the longitudinal and circular muscle layers of the canine proximal colon was investigated by light and electron microscopy. Unique smooth muscle bundles, referred to as "oblique" muscles, were arranged in branching/anastomosing bundles, forming a network intermeshed with the nerve plexus and vasculature. These smooth muscles were concentrated along the ganglia and primary connectives of the myenteric plexus, thus showing a periodic distribution roughly corresponding to that of the ganglia. The oblique smooth muscle bundles bridged the distance between the circular and longitudinal muscle layers and blended into the inner aspect of the longitudinal muscle layer and the outer aspect of the circular muscle layer. A few oblique muscle cells occurred within the sheath of the ganglia and primary strands, i.e., perineurium. Oblique muscles may serve to electrically couple the circular and longitudinal muscle layers, thus explaining the synchronous electrical activities of these muscles. It is possible that the pacemaker activity in the myenteric region is generated by these muscle cells. Oblique muscles may also serve to protect nerve elements and the vasculature from the mechanical stress of peristalsis.

Animals↗
PubMed1978

Comparative aspects of membrane properties and innervation of longitudinal and circular muscle layers of rabbit jejunum.

Longitudinal muscle of the rabbit jejunum usually generated burst discharges, whereas circular muscle mainly generated slow potential change. Membrane potential was higher, and the space and time constants were larger in circular muscle than in longitudinal muscle. Current-voltage relationship exhibited anomalous rectification by depolarization of membrane in longitudinal muscle cells, and delayed rectification in most circular muscle. Excitatory junction potentials (e.j.p.s) were recorded from both muscles and inhibitory junction potentials (i.j.p.s) were recorded from only circular muscle. The e.j.p.s consisted of muscarinic e.j.p.s and atropineresistant e.j.p.s, but only the latter were recorded from circular muscle. The i.j.p.s were not affected by either or both alpha- and beta-blockers, but were blocked by TTX. From mechanical and electrical responses of both muscle layers induced by field stimulation, it was postulated that four different types of nerve fibres innervate the jejunum muscles: (I) cholinergic excitatory nerves, (II) non-adrenergic and non-cholinergic inhibitory nerves (or purinergic nerves), (III) non-adrenergic and non-cholinergic excitatory nerves and (IV) adrenergic inhibitory nerves. In the longitudinal muscle, (I) was dominant, but (II) was also found. In the circular muscle all four types were found to exist. Effects of adrenergic nerve stimulation on the membrane potential was not detected by stimulation below 10 Hz, although externally applied noradrenaline at 5.9 X 10(-8)m had a relaxing effect.

Action Potentials↗
PubMed1997

MR features of longitudinal tears of the peroneus brevis tendon.

OBJECTIVE: Our objective is to describe the characteristic MR imaging features of longitudinal tears of the peroneus brevis tendon and to describe pathologic conditions and normal variants that are associated with these tears which may require surgical intervention at the time of primary tendon repair. MATERIALS AND METHODS: We retrospectively reviewed 10 MR images of asymptomatic volunteers and 31 MR images of 27 patients with evidence of longitudinal splits of the peroneus brevis tendon. Seven of these cases were surgically proven. In addition, we assessed five pathologic conditions and normal variants: lateral collateral ligamentous tears; injuries to the superior peroneal retinaculum; low-lying muscle belly of the peroneus brevis tendon; peroneus quartus muscle; and convex, flat, or irregular retromalleolar groove. RESULTS: In the patient's group, we saw longitudinal splits as clefts and an irregularity of the contour of the peroneus brevis tendon with (71%) and without (29%) signal changes on proton density-weighted and T2-weighted MR imaging sequences. Divisions of the split tendon assumed a characteristic C-shaped configuration that partly enveloped the peroneus longus tendon. Fifteen cases revealed other pathologic conditions and normal variants known to be associated with or to predispose to tears of the peroneus brevis tendon. These include ankle ligamentous tears (n = 3); abnormal superior peroneal retinaculum (n = 4); low-lying muscle belly of the peroneus brevis tendon (n = 1); peroneus quartus muscle (n = 2); and convex, flat, or irregular retromalleolar groove (n = 15). MR imaging revealed tears in all patients with surgical proof (n = 7). CONCLUSION: MR imaging is a useful technique for revealing longitudinal tears of the peroneus brevis tendon as well as showing anatomic and pathologic factors associated with or predisposed to tears.

Adult↗
PubMed2026

Longitudinal Repeated Protein Measurements in a Multiethnic Cohort Identify Novel Diabetes Biomarkers That Reveal Unique Disease Pathways.

There is up to a fourfold increase in diabetes biomarkers identified with longitudinal repeated versus single time point proteomic measurements. The increase in biomarkers identified with longitudinal repeated measurements is supported by a similar proportion being nominated as causal for type 2 diabetes with Mendelian randomization. Proteins unique to the longitudinal repeated analyses highlighted biological pathways (e.g., posttranslational protein modification and cellular structure and cycle regulation) that were distinct from pathways enriched among the shared proteins (e.g., small-molecule metabolic and catabolic processes). Longitudinal protein measurements identify additional novel disease biomarkers and disparate biological pathways compared with single measurement analyses.

Journal Article↗